Cyclonic apparatus



Feb. 6, 1968 e. w. DINGUS 3,367,090

CYCLONIC APPARATUS Filed Sept. 1966 United States Patent Ofiiice3,367,090 Patented Feb. 6, 1968 3,367,090 CY'CLDNIC APPARATUS George W.Dingus, Pampa, Tex., assiguor to Cabot Corporation, Boston, Mass., acorporation of Delaware Continuation-impart of application Ser. No.453,060,

May 4, 1965. This application Sept. 6, 1966, Ser.

7 Claims. (Cl. 55-293) ABSTRACT F THE DISCLOSURE The present inventionrelates broadly to novel selfpurging cyclone apparatus. Broadly, saidapparatus comprises a cyclone chamber comprising a multi-perforatedouter supporting structure and an elastomeric liner attached to theinterior thereof. During operations, said liner flexes therebymaintaining the cyclone apparatus free from accretion of solids therein.

This application is a continuation-in-part of copending US. applicationSer. No. 453,060, filed May 4, 1965, now abandoned.

The use of cyclonic apparatus for the collection and/ or classificationof particulate solids from gaseous streams containing solids entrainedtherein is well known. Said apparatus has been found to be particularlyvaluable in processes wherein particulate solids such as carbon black,titanium dioxide, silicon dioxide, and the like are produced.

Generally speaking, cyclonic collection apparatus normally functions asfollows: a fluid stream containing entrained solids is charged into anenclosed cylindrical or conical zone and caused to spin therein. Saidspinning can be caused in any suitable manner although it is usuallyaccomplished by charging the fluid stream into said enclosed cylindricalzone tangentially. The forces imparted to the solid particles by thespinning motion urges said particles outwardly and depending upon thesize and/or mass of the particles and the velocity of the fluid, theparticles tend to segregate outwardly and downwardly and to eventuallyfall to the base of the zone. The remaining fluid stream, freed fromsolid materials, is exited from the enclosed zone while the solidmaterials at the base of the zone are removed in any suitable manner.

One of the problems often encountered in operation of cyclonic apparatusresides in the tendency of particulate solids to deposit on the internalsurfaces thereof. Said problem is generally particularly acute when thefluid stream undergoing treatment in said apparatus is a hot gas and thesolid particles entrained therein tend to agglomerate such as, forexample, is usually the case during the collection of freshly producedcarbon blacks and pyrogenic metal or metalloid oxides. Accretions ofparticulate solids on the internal surfaces of cyclonic apparatus caneventually partially or wholly plug said apparatus. Moreover, saidaccretions can alter the flow pattern of the gas stream therein therebyultimately resulting in partial or complete loss of collecting orclassifying effi: ciency. In accordance with the present invention,however, these problems have largely been eliminated.

Accordingly, it is a principal object of the present invention toprovide improved apparatus for the separation and collection ofparticulate solids from fluid streams.

It is another object of the present invention to provide a novel meansfor preventing the accretion of particulate solids on the internalsurfaces of cyclonic apparatus.

' Other objects and advantages of the present invention will in part beobvious and will in part appear hereinafter.

In accordance with the present invention it has been discovered thataccretion of particulate solid materialxon internal surfaces of acyclonic apparatus is substantially eliminated when said apparatuscomprises a chamber comprising (1) a perforated exterior supportingstructure, and (2) an elastomeric material interior surface.

The present invention Will be more readily understood when. reference ishad to the accompanying drawings forming part hereof wherein:

FIGURE 1 is a schematic longitudinal illustration of one embodiment ofthe present invention in which the chamber portion of cycloniccollection apparatus comprises interior surfaces comprising anelastomeric material supported by an exterior perforated structure; and

FIGURE 2 is a cross-sectional schematic view of a portion of a cycloniccollection apparatus chamber wall wherein the elastomeric material innersurface of said chamber comprises two forms of elastomeric material.

In a typical operation of apparatus of the present in vention, referringnow to FIGURE 1, a fluid stream containing entrained particulate solidsis charged tangentially into the cyclone chamber through conduit 3. Theentrained solids tend to migrate toward chamber. wall inner surfaces 7and to fall downwardly, and are eventually exited through outlet 9. Thefluid stream, freed from at least a portion of said solids courses outof the chamber through conduit 11.

Normally in such an operation, solids contact at least a portion of saidsurfaces 7 and tend to deposit or accrete thereon. However, in thepresent novel apparatus, internal surfaces 7, comprising suitableelastomeric material, tend to flex during operations in accordance withfluctuations in pressures within the apparatus. Said fluctuations can becaused intentionally, such as by periodically increasing or augmentingthe flow rate of the fluid stream. However, frequent fluctuations ininternal pressure are normally inherent in cyclonic separation and/orcollection processes and are usually of sufllcient amplitude to providethe desired flexure of the elastomeric material through the perforatedsupporting structure. Thus, the purging is usually effected withoutrequirement for additional process steps or equipment.

For the purposes of the present invention, the term elastomeric materialgenerally includes any material which conforms to the criteria set forthby Fred W. Billmeyer in Textbook of Polymer Chemistry, page 154, 1957,Interscience Incorporated, New York, which criteria are that thematerial:

(1) Stretch rapidly and considerably under tension with little loss ofenergy as heat,

(2) Exhibit high tensile strength and high modulus when fully stretched,

(3) Retract rapidly, exhibiting the phenomenon of snap or rebound,

(4) Recover its original dimensions substantially fully on release ofstress, exhibiting phenomena of resilience, creep resistance and lowpermanent set.

Additionally, elastomeric materials suitable for use as the interiorsurfaces of the cyclonic apparatus chambers of the present inventionshould be (a) capable of with: standing the temperatures, pressures andstresses incurred during operations and (b) substantially inert withrespect to the substances encountered during operations. The choice ofsaid elastomeric material will therefore be dic-, tated to an extent bythe particular fluid stream to be treated. Specific examples ofelastomeric materials that can frequently be utilized for internalsurfaces are: natural gum rubber; 1,3 cis-butadiene rubber; siliconerubber; butyl rubber; butylene-acrylonitrile rubber; butadienestyrenerubber; neoprene and the like. Generally preferred, however, when arelatively inert solid/gas stream system is to be treated is natural gumrubber.

The thickness of the elastomeric material utilized in the presentinvention is subject to considerable variation" and is dependent to someextent upon the nature of the support upon which it is mounted.Specifically, the thickness of the elastomeric material should normallyrange from about & of an inch to about inches. Preferred, however, is athickness range of from about li of an inch to about 1 inch.

It should be noted that foamed elastomers such as flexible polyurethanefoam can also comprise the inner walls of the present invention. Saidfoam can be afiixed to the supporting structure by itself or preferablycan have a substantially homogeneous elastomeric sheet such as neoprene,natural gum rubber or the like bonded to the innermost surfacethereof asfllustrated in FIGURE 2.

The general design specifics of the outer supporting structure 15 of thecyclonic apparatus, such as size, material, etc., are generally notcritical. However, it can be said that normally structure 15 should berelatively rigid in order that variations of internal pressure duringoperations can effect fiexure of substantially only the elastomericmaterial forming internal surfaces 7. Obviously, structure 15 must alsobe capable of withstanding the pressures and stresses incurred duringsaid operations. Specific materials that are generally suitable for thefabrication of the outer supporting structure are stainless steel, castiron, cast steel, aluminum, ceramic compositions and the like. When thesolid/fluid mixture to be separated is relatively cool it will often besatisfactory to utilize thermoplastic materials as materials ofconstruction for the supporting structure, such as variousacrylonitrile-butadiene-styrene copolymers, polyamides, polyvinylchloride, polyacetals, and the like.

As is illustrated in FIGURE 1, it is important that perforations 17 bepresent in outer supporting structure 15. Said perforations allowintemalsurfaces 7 to flex substantially more freely than would be thecase if surfaces 7 were to be supported by a substantially continuousouter structure. Although the precise area of elastomeric material leftunsupported by the perforations in the supporting structure is subjectto substantial variation, it is generally desirable that the total areaof the perforations comprise an area at least about 30% and preferablyabove about 50% of the area of the perforated supportingstructure.

The elastomeric material comprising the internal surfaces is generallyafiixed to the outer supporting structure by any suitable method, suchas by bonding with an adhesive and/ or vulcanizing said elastomericmaterial directly to the outer structure. The elastomeric material canalso be mechanically fastened to the outer structure such as byriveting, wire stapling, etc.; however, a continuous bond, such as isformed when said material is vulcanized, glued and the like to theperforated supporting structure is much preferred.

There follow a number of non-limited examples:

Example 1 black at a loading of about 100 grains carbon black/ft? gas ischarged tangentially into standard cyclone apparatus at a rate of about400 s.c.f.m. The cyclone utilized has a 3 foot 4 inch cylinder length, 2foot cone length, is 20 inches in diameter at the juncture cylinder andcone, and comprises .a A-il'lCll welded rolled continuous steelstructure having no elastomeric material upon the interior surfacesthereof. The internal pressures incurred during op erations over aperiod of about 2 days are measured manometrically and are found to varybetween about6 and 10 inches H O. After 36 hours, the operation isdiscontinued and the internal surfaces of the apparatus are examined andare found to have substantial carbon black accretion thereon. Saidaccretion is removed and collected and is found to weigh about 20 lbs.and to occupy a volume of about 2 cubic feet.

Example 2 This example is a duplicate of Example 1 with the exceptionthat to the interior walls of the cyclone there is bonded of an inchthick gum rubber sheeting. After a 36-hour run under substantially thesame operating conditions as in Example 1, it is found that about 7 lbs.of carbon black have accumulated on the internal surfaces thereof.

Example 3 This example is a duplicate of Examples 1 and 2 with theexception that in this example the cyclone apparatus comprises a %6 ofan inch thick sheet of gum rubber bonded to the interior surface of asupporting perforated steel outer structure as illustrated in FIGURE I.Said outer structure has diamond shaped perforations approximately 2 /2inches in length and 1 /2 inches in width, the edges of whichperforations are spaced about A; of an inch from each other. Aftercontinuous operation for about 36 hours, internal surfaces 7 were foundto be substantially free of solid accumulation.

It is believed, although there is no intent to be bound by thisexplanation that accretion of particulate solids on the internalsurfaces of cyclonic apparatus normally consists of particles whichadhere relatively loosely to one another. Usually, therefore, saidaccretion is of a friable nature.

Thus, when a fault such as a crack, break or the like is caused to occurin said accretion there is normally a decided tendency for saidaccretion to crumble to the extent that complete purge thereof occurs.It is further believed that the improved cyclone apparatus of thepresent invention allows sulficient flexibility of said walls duringoperations to result in the formation of said faults thereby resultingin substantially continuous purge.

Obviously, many changes can be made in the above illustrative examplesand description and in the apparatus illustrated in the accompanyingdrawings without departing from the scope of the present invention. Forinstance, only those portions of the interior surfaces which tend tocollect accretions thereon need comprise the elastomeric material innersurface supported by the perforated outer structure. It should be noted,when such an embodiment of the present invention is contemplated thatthe portions of the cyclone apparatus to be treated by perforations andelastomeric lining should also adhere to the minimum perforated areacriteria as described hereinbefore. Normallly, however, it is generallypreferred that substantially the entire cyclone apparatus comprise thechamber walls of the present invention.

Also, the cyclone can be modified in many ways, in order to fit anyparticular process requirement. Thus, as mentioned hereinbefore, theexamples are not limited to the treatment of streams comprising onlycarbon black and gases but also relate to streams comprising otherparticulate solids and fluids. Thus, the benefits of the presentinvention also accrue when solids are separated from fluid streamscontaining titanium dioxide, silicon dioxide or the like.

Also, fluctuations of internal pressure during opera tions can beaccomplished or augmented by any suitable method. Accordingly, it isintended that the above disclosure be regarded as illustrative and as inno way limiting the scope of the invention.

What is claimed is:

1. In cyclone apparatus of the type comprising a cyclonic chamber, meansto introduce a fluid stream containing entrained particulate solidsthereinto and means to exit a fluid stream therefrom, the improvementwhich comprises a wall defining said chamber, said wall comprising anouter supporting structure having a plurality of perforationstherethrough and an inner liner comprising an elastomeric materialhaving a thickness of between about of an inch and about 5 inchesattached to said outer supporting structure, the total area of saidperforations comprising at least about 30% of the area of saidsupporting structure having perforations therein.

2. The apparatus of claim 1 wherein said perforations arediamond-shaped.

3. The apparatus of claim 1 wherein the total area of said perforationscomprises at least about 50% of the area of said supporting structurehaving perforations therein.

4. The apparatus of claim 1 wherein the thickness of the elastomericmaterial liner is between about ,6 of an inch and about 1 inch.

5. The apparatus of claim 1 wherein substantially the entire cycloneapparatus chamber comprises said perforated supporting structure and theelastomeric inner liner.

6. The apparatus of claim 1 wherein said elastomerie liner iscontinuously bonded to the interior of said supporting outer structure.

7. The apparatus of claim 1 wherein said elastomeric liner attached tothe interior of said supporting structure comprises (1) a layer of anelastomeric material foam adjacent said supporting structure, and

(2) a layer of substantially unfoamed elastomeric material continuouslybonded to the free surface of said foam layer.

References Cited UNITED STATES PATENTS Becker --435 Shaw 1 61221 XSchatfer 161-222 X Kuhn 16l-221 X Hubbard et a1 161221 Braun et a1.55435 X Demeter.

Wehn et a1. 55435 X Giesse 55-455 X Charbonneau 161190 Brown et a1.55---435 X Belgium.

HARRY B. THORNTON, Primary Examiner. S. W. SOKOLOFF, Assistant Examiner.

